Reverse flow acoustic generator spray nozzle



Jan. 10, 1967 w. K. FORTMAN REVERSE FLOW ACOUSTIC GENERATOR SPRAY NOZZLEFiled April 19, 1965 FIG. I 1/ 3 Sheets-Sheet 1 ACT! VE G'AS' ININVENTOR. WILLIAM K. FORTMAN ATTOIKRNEY Jan. 10, 1967 w. K. FORTMANREVERSE FLOW ACOUSTIC GENERATOR SPRAY NOZZLE Filed April 19, 1965 3Sheets-Sheet 2 INVENTOR.

WILLIAM K. FORTMAN film/ml ATTORNEY Jan. 10, 1967 w. K. FORTMAN3,297,255

REVERSE FLOW ACOUSTIC GENERATOR SPRAY NOZZLE Filed April 19. 1965 3Sheets-Sheet 3 United States Patent Ofiice 3,297,255 Patented Jan. 10,1967 3,297,255 REVERSE FLOW ACOUSTiC GENERATOR SPRAY NOZZLE William K.Fortman, Essex, Conn, assignor to Astrosonics, Inc., Syosset, N.Y. FiledApr. 19, 1965, Ser. No. 449,189 15 Claims. (Cl. 239102) This applicationis a continuationin-part of my copend-ing application, Serial No.288,266 for a Reverse Flow Acoustic Generator Spray Nozzle, filed June17, 1963.

This invention relates to high volume liquid aerosol generating devicesemploying acoustic generators.

As is well known in the art, for example as taught in U.S. Patent No.2,519,619 granted to Yellott et al., a high energy vibratory sound fieldis produced when a tuned cavity resonator is excited into resonanceunder the influence of an impinging high velocity jet of gas. Theresonator will periodically load and unload violently at the imposedresonator frequency. Thus the high velocity jet stream is converted ortransduced into a high intensity sonic beam.

Prior art spray devices employing Yellott et al. and relatedHartmann-type acoustical generators, have directed the liquid generallytowards the resonator cup. As a result thereof, the resonator cup tendedto clog particularly if viscous liquids were being handled.

Further the extended position of the resonator cup of the prior artpresents an aerodynamic influence on operation of the apparatus since itis directly in the path of the sprayed materials and accordingly subjectto eroding and corroding influences. The shortcomings of thisarrangement may be manifested in several ways. When the spray materialused is an acid, salt, molten metal, etc., there will be rapid wearingof the resonator cup necessitating frequent changes or repairs inaddition to inaccurate and unpredictable operation. When thixatropicmaterials, such as gelatins, waste sludge, coffee syrups, liquors, etc.,are sprayed, a tendency exists for coatings to build up therebydistorting the aerodynamic path and sound field, as Well as disturbingthe atomizing characteristics.

There is still another characteristic of the conventionalopposed-resonator construction that lends itself to improvement.Heretofore, the resonator cavities have been cup-shaped, defined by abottom wall transverse to the longitudinal axis of the generator and acylindrical side wall parallel to the longitudinal axis of thegenerator. With this arrangement, there is a tendency to emit the mostintense sound waves at right angles to the longitudinal axis, thusrequiring the addition of a reflector to direct and concentrate thesound waves forward of the generator.

The present invention is directed towards providing a more rugged devicecapable of operating efiiciently even with materials heretoforeconsidered impractical because of their viscosity or corrosiveness. Inthe present invention, the resonator is made an integral part of thebody and is contained therein. This assures a rugged, durableconstruction, good reflectivity and a more coherent sound field.Further, the fabrication of the device is simplified by forming the airinlet passage by a drilling operation and avoiding the use of a costlyinternally tapered passageway to provide a restricted orifice.

The generator of the present invention is versatile in that theresonator cavity can be angled with respect to the longitudinal centralaxis of the generator in accordance with or to satisfy the requirementsof a particular application. The proper selection of resonator angleassumes the formation of a particular spray angle (sound emission atsource) at maximum resonance- By using the construction of the presentinvention, air and sound by reflection and rebound reflection (airbounding oil a surface) will tend to flow at right angles from the wallof a resonator resulting in an overall spray cone included anglesuitable for use with many of the more difficult spraying problems.

The construction of the present invention insures a more rigidly mountedresonator which, in turn, produces better sound reflection. Since theresonator is enclosed within the body of the generator, and in fact ispart of the generator :body, there is a substantial mass behind it. Thisis in contrast with the prior art which externally supports the rsonatoron a slender axial stem. Further, the improved location of the resonatormakes it less subject to plugging, wear, corrosion and otherdeterioration which tend to shorten its effective life and impair itsaccuracy.

Working in cooperation with the relocated resonator is a reversingdeflector. This novel means of directing the high velocity gas into theresonator cavity sets the gaseous medium into resonance. The reversingdeflector of the present invention comprises in part a toroid having aconcave portion spacedly opposing the gas and spray material outlets asWell as the internally located resonator cavity. The concave portion ofthe toroid effectively reverses the gas flow and directs it into theresonator cavity wherefrom its emanates at substantially right angles tothe wall of the resonator to impinge upon and break up the spraymaterial. The shallow toroid is situated on the longitudinal axis of thegenerator and may be adjusted closer to or further away from the nozzlearea. This provides an eflective control of the exiting gas annulararea. The shallowness and small size of the reversing reflectorvirtually eliminate any obstruction in front of the resonator andthereby overcome a major objection to the prior art generators, namely,the externally supported resonator.

In one form of the present invention, the resonator and toroid aresurrounded by a cavity or reservoir for liquids which may include fluidmetals, emulsions, sludges, plastics, or other viscous or nonviscousmaterial provided it will flow. Means to discharge the sprayablematerial, such as an annular opening, a series of holes, orificeinserts, or slots, are positioned proximate the resonator so that eitherby gravity or under pressure, the sprayable material is caused to flowpast the acoustically disturbed active gas stream and is broken upthereby. Thus, another major shortcoming of prior art generators isovercome in that the resonator is no longer located downstream and inthe way of the sprayed material. While this is not of prime importancewith the less viscous fluids, it is significant with the viscousmaterials such as fluid metals, :gelatins, wastes, etc.

In another form of the invention, the liquid or fluid port is centrallylocated on the longitudinal axis of the body and both the resonator andreversing deflector are concentrically positioned thereabout. Thisconstruction with a substantialy linear central bore permits a smootherflow therethrough of particularly viscous materials to be atomized suchas sludges having high solids content. A further advantage is whenabrasive materials are handled, the straight through flow path avoidsthe wear which results from the flow of such "material through the bodyof the embodiment of FIG. 1. In addition, the stnlcture of thisembodiment permits the positioning of the fluid outlet port downstreamof both the resonator and the reversing deflector so that the likelihoodof contamination is minimized.

The present invention contemplates among other things, theuse of arelatively small reversing deflector and a large spray material exitarea, thus preventing interference with the spray pattern. Further, thecontinuous D.C. blast of gas will prevent any particle from lodging inthe gas outlet adjacent the reversing deflector, and as the generator isfrequently used in the vertical position (nozzle downward) the materialto be sprayed flows downwardly by gravity past the acousticallydisturbed active gas stream where break-up will occur. Further, sincethe cavity opening faces downwardly, there is no tendency for materialsto collect therein.

Accordingly, it is an object of the present invention to provide a morerugged acoustic generator.

It is another object of the present invention to provide an acousticgenerator with a resonator substantially enclosed therein.

An additional object is to provide an acoustic generator with an annularresonator.

A further object is to associate a reversing deflector with said annularresonator.

Still another object is to construct an acoustic generator capable ofaccommodating some of the more viscous or corrosive fluid materials.

Another object is to provide an acoustic generator requiring lesscritical machining procedures.

An additional object is to provide an acoustic generator capable ofgenerating a variety of spray cone angles.

Another object is to provide an acoustic generator that produces animproved sound reflection.

Still another object is to construct a spray device employing anacoustic generator less subject to plugging, wear, corrosion and othermaltreatment.

A further object is to provide an acoustic generator with a minimum ofobstruction in front of the resonator.

An additional object is to provide an improved acoustic generatorwherein the fluid outlet port is centrally disposed relative to aconcentric resonator and reversing deflector or wherein the fluid outletport is concentrically disposed about the resonator and reversingdeflector.

A further object is to provide an improved acoustic generator having asubstantially straight through flow path for materials to be atomized.

These and other objects and advantages of the present invention will bepointed out with particularity or will be evident from the followingdescription and the drawing appended thereto in which:

FIG. 1 is an elevational view in section of the present inventionacoustic generator.

FIG. 2 is a view from below the acoustic generator of FIG. 1 taken alongline 22.

FIG. 3 is a fragmentary elevational view in section illustrating theflow pattern of the acoustic generator of FIG. 1.

FIG. 4 is a view similar to FIG. 2 illustrating an alternative spraymaterial nozzle having elongated slots.

FIG. 5 is a view similar to FIG. 2 illustrating another alternativespray nozzle having replaceable jet orifices.

FIG. 6 is a partial elevational view illustrating radial aperturescomprising the spray material nozzle.

FIG. 7 is a partial elevational view in cross section illustrating acylindrical spray material nozzle parallel to the longitudinal axis ofthe acoustic generator and the spray pattern created thereby.

FIG. 8 is a partial elevational view in cross section illustrating anoutwardly flaring spray material nozzle and the spray pattern createdthereby.

FIG. 9 shows schematically a source of molten metal.

FIG. 10 is a plan view of an alternative embodiment of the presentinvention; and

FIG. 11 is a sectional elevation view taken along line 1111 of FIG. 10and illustrating a construction wherein the fluid outlet port iscentrally disposed about the longitudinal axis of the acoustic generatorand the resonator and reversing deflector are concentric thereabout.

Referring now to the drawing, and in particular to FIG. 1 and FIG. 2,there is shown an acoustic generator generally designated as 10. Thegenerator is comprised of three main components, namely, a body portion12 having an integral gas nozzle 14 and resonator 16 both coaxial andconcentric thereto, a reverser valve 18 in axial spaced opposition tothe gas nozzle and resonator, and finally a fluid nozzle 20, radiallyspaced from and coaxially surrounding the resonator.

Body portion 12 has at its upper end 22 a threaded inlet port 24 for theliquid material which is to be sprayed. Port 24 communicates directlywith fluid nozzle 20 by means of passageway or duct 26 disposedlongitudinally within body 12. An active gas duct 28 is formedconcentrically with the longitudinal axis of the generator in the lowerportion thereof, and at its upper, end terminates in an inlet port 30formed in the side wall of the generator. By definition, the active gasand liquid material flow downstream from inlet ports 30 and 24,respectively. This construction permits concentricity of the gas andfluid nozzles as well as the resonator and reversing deflector withoutunduly increasing the size of the apparatus. Body portion 12 is furthercharacterized by a reduced diameter cylindrical portion 32 having aconical end 33 which, in conjunction with hollow gas nozzle 14,similarly conical, defines a fluid reservoir '34. The orifice 36 ofreservoir 34 is radially spaced from and substantially covers resonator16 formed near the lowermost end of body 12. Gas nozzle 14 is threadablysecured to body 12 and has disposed therebetween a sealing gasket 38.

Resonator 16, in the form of an inclined annular channel, is comprisedof an inner side wall 40 which, in the embodiment shown, starts at the'bottom of body 12 adjacent gas nozzle 14 and extends upwardly andoutwardly to terminate in an arcuate end wall 42. The outer side wall44, a continuation of end wall 42, is in spaced parallel relation toinner side wall 40 but of somewhat shorter length, terminating slightlybelow the open orifice end 36 of fluid nozzle 20. In the particularembodiment illustrated in FIG. 1 and FIG. 2, wall 44 extendsapproximately 0.034 inch below the end of fluid nozzle 20 there- 'byleaving a small exposed portion of inner wall 40 while the end wall 42is contained within the confines of fluid nozzle 20. Angle A, theinclination of resonator 1'6 with respect to the longitudinal axis ofthe generator, may be varied for different applications. In theillustrated embodiment, the angle is approximately 17, thus producing anincluded cone angle for spray material of approximately 146. By way ofillustration, if angle A were increased to 20, the included cone anglewould be The annular gap of approximately 0.020 inch between the fluidmaterial nozzle and the outside surface of the resonator forms theannular fluid orifice 36 adjacent the inclined resonator 16.

Reversing deflector 18 is comprised of an elongated stem 50 adjustablypositioned at its upper end within body 12 by means of screw threads 52and retained in a particular axial position by set screw 54. Deflector18 is accurately centered on the longitudinal axis of the generator bymeans of spider 56 fitted into gas duct 28. The spider support assuresaccurate positioning of the reversing deflector while still permittingadequate flow of gas therethrough. By loosening set screw 54, deflector18 may be threadably adjusted either closer to or farther away from boththe resonator and the fluid orifice. This would have the effect ofchanging the size and shape of the constricted gas nozzle which isdefined by the juxtaposition of the resonator and reversing deflector.For purposes of orientation, the reversing deflector is said to bedownstream of the resonator. At its opposite end, deflector 18 isprovided with a toroid 58 having a concave reflecting surface 60 spacedproximate to and in opposition with gas duct 28 of nozzle 14. Surface 60of toroid 58 effectively reverses the flow of the incoming gas directingit upstream into resonator 16, from which it is again redirectedoutwardly to impinge on the downwardly flowing supply of fluid material.As seen in FIG. 3, the downs a-25s ward, outflow of fluid materialsurrounds the resonator and is formed into a spray cone during thedischarge cycle of the resonator. It should be noted that since theresonator, is formed directly in the body of the generator, it is ofvery rugged construction, capable of withstanding considerable shock.Further, since the resonator is frequently used inverted, that is, withthe nozzles pointing down, there is little likelihood of an accumulationof fluid material collecting therein. This is of importance in that thereliability of the apparatus with respect to accuracy and repetition ofoperation is maintained due to the resonator being uncontaminated. Inaddition, the proximate location of all cooperating elements of theapparatus assures maximum utilization of sonic energy.

While the embodiment hereinabove described contains an annular orificefor the efiiux of fluid material, it also contemplates providingalternative structures all having the common factor of downwardlydispensing a fluid material that is impinged upon by a reverselydirected beam of sonic energy. One such structure is illustrated in FIG.4 wherein fluid nozzle 20a is provided with elongated slots 62 in placeof annular orifice 36. It is to be understood that the size and quantityof slots may be varied to meet the requirements of particularapplications. In addition, the shape of the slots may be altered toinclude circular apertures. In FIG. 5 there is shown an alternativestructure wherein jet nozzles 64 are secured in the lower face of fluidnozzle 20b. The advantages provided by the jet nozzles are that they maybe selected from a range of sizes and be easily replaced if found to bedefective. Orifice jets or jet nozzles provide individual filaments ofliquid which at times have advantage for very viscous or corrosivefluids. In viscous applications, a thin filament is sometimes preferableto provide a sausagelike bead of uniform diameter. In corrosiveapplications, small openings are exposed to rapid wear and therefore theadvantage of easily replacing the opening is obvious.

.FIG. 6 illustrates a fluid nozzle 200 having a plurality of apertures66 located so as to provide a radially outward flow of fluid material asopposed to the substantially axial flow of theprevious embodiments.Radial ports, jets, or orifices, can be advantageous for producing verywide cones, such as shown, for use in gas cooling operations or forexceptionally viscous materials where the radial spray pattern preventsreagglomeration. In this embodiment, plug 67 closes the annular passage.

In the embodiment of FIG. 7, nozzle 20d provides a cylindrical curtainof fluid parallel to and concentric with the longitudinal axis of thegenerator. Whereas the prior embodiments were constructed with conicalend portions on the body of the generator and the fluid nozzle, theembodiment of FIG. 7 has straight end portions that are concentric withone another and with the gas nozzle. This provides for adjustment of thenozzle in relation to the resonator whilst keeping the liquid flowconstant. Some adjustment to the cone angle is possible by varying thelength of the surrounding sleeve. In the embodiment shown, a narrow conepattern is obtained. As before, the gas flow direction is reversed bymeans of a deflector.

There is shown in FIG. 8 still another embodiment of the presentinvention. Nozzle 20e is flared outwardly at the lowermost end portionthereof providing a medium bushy cone-shaped spray pattern. In flaringout the annular liquid orifice, a medium spray pattern is provided.

If the liquid nozzle is adjusted it acts like a valve and could in theextreme shut off the liquid flow completely. The device of thisinvention may be used to spray liquid metal. In FIG. 9 there is shownschematically a metal melting means 90 connected to a nozzle 10.

FIG. 10 and FIG. 11 illustrate an embodiment of the present inventionparticularly Well adapted to the atomization of extremely viscousmaterials or slurries with high solids and/ or abrasive content.Acoustic generators employing the configuration herein described aredesigned line.

6 to eliminate the problems of clogging and material buildup so oftenencountered. In this embodiment, the resonator and reversing deflectorsurround the liquid feed orifice which is downstream thereof and iscompletely unobstructed.

Acoustic generator is comprised of a body portion 102 having externalthreads 104 at the upper end thereof. Threads 104 mate with internalthreads on a gas supply source 106 shown in phantom in FIG. ll. Gasenters body portion through a plurality of inlet ports 108 equallyspaced from each other on a common diametrical center- Bores 108terminate in a common chamber 110 having an inwardly tapering wall,thelowermost portion of which defines a gas nozzle 112.

Body portion 102 is further provided at its lower end, with an annularresonator 114 having inclined walls 116. As in the previous embodiments,the resonator is wholly contained within the body portion in order toprovide rigidity. It will also be seen that both the gas nozzle and theopen end of the resonator terminate in approximately the same plane.

Combination reversing deflector and fluid inlet means 118 are centrallydisposed on the longitudinal centerline of acoustic generator 100.Support means 118 is comprised of a hollow tube 120 having asubstantially linear central bore 121 and external threads 122 at theupper end thereof. Threads 122 are adapted to engage similar threads ona fluid source 124 shown in phantom in FIG. 11. Another set of externalthreads 126 are provided on the central portion of tube 120 whereby thesupport tube may be adjustably secured in threaded central bore 128 ofbody member 102. A reversing deflector 130 having a concave reflectingsurface 132 is integrally formed at the bottom end of tube 120 in spacedopposition to the gas nozzle 112 and the resonator 114. By thisconstruction, the resonator, the gas nozzle and the reversing deflector,are concentrically and coaxially arranged about a central fluid orifice134.

The embodiment described hereinabove is particularly useful with highlyviscous fluids. Centralization of the fluid passage provides a smoothunobstructed flow. In addition, the construction of this embodimentpermits the positioning of the fluid nozzle below the plane of theresonator and thus reduces the possibility of resonator contamination.The viscous fluid or slurry is directed axially, the gas is deflectedoutwardly, and the sonic energy is concentrated on the longitudinalcenter line of the acoustic generator whereby it may act on and atomizethe fluid at a point below the fluid nozzle.

It should be understood that with each of the nozzle configurationsenumerated hereinabove, any one of the orifice arrangements of theprevious embodiments may be employed.

There has thus been set forth several variations of a reverse flowacoustic generator spray nozzle, each of which incorporates ruggedconstruction, due in part to the resonator being substantiallyself-contained internally of the generator body. This configuration alsoprovides a resonator inverted from the position of the prior art andthus assures more trouble-free and accurate performance. An additionaladvantage accures in that no additional reflecting surface is requiredsince the resonator itself, in cooperation with the reversing deflector,is variable and either one or both elements may be altered in shape orposition to meet the changing requirements of different applications.

There has been disclosed heretofore the best embodiments of theinvention presently contemplated and it is to be understood that variouschanges and modifications may be made by those skilled in the artwithout departing from the spirit of the invention.

What is claimed is:

1. A liquid spraying apparatus employing an acousticgeneratorcomprising:

(a) a body member including independent gas and liquid cavities incommunication with gas and liquid inlet ports, respectively, the gas andliquid cavities being concentrically disposed with respect to eachother;

(b) a gas dispensing outlet extending from said body member in adownstream direction, said gas dispensing outlet having a borecontiguous with the gas cavity;

(c) a gas flow reverser member rigidly supported from said body memberin spaced relation to said gas dispensing outlet, said reverser memberbeing provided with a concave upwardly facing annular groove inopposition to said gas dispensing outlet, the annular groove beingnonresonant to the flow of gas therethrough;

(d) an annular cavity resonator deployed in said body member coaxialwith said gas dispensing outlet; and

(e) liquid nozzle orifice means carried by said body member, said liquidnozzle orifice means being deployed in concentric relationship to saidcavity resonator and in communication with the liquid cavity.

2. The apparatus in accordance with claim 1 wherein said liquid cavityis a hollow tube centrally located within said body member, said cavityresonator and said flow reverser member being disposed concentricallythereabout.

3. The apparatus in accordance with claim 2 wherein said liquid nozzleorifice means is positioned downstream with respect to said cavityresonator and said flow reverser means.

4. The apparatus in accordance with claim 1 wherein the gas cavity iscentrally located and said liquid nozzle orifice means is deployedconcentrically about said resonator cavity and in communication with theliquid cavity.

5. The apparatus of claim 1 including means to vary the spacing betweenthe said gas dispensing outlet and the said gas fiow reverser memberwhereby the velocity of the gas leaving the reverser may be varied for agiven gas input pressure.

6. The apparatus of claim 1 wherein said reversing means comprises asupport member having screw thread axial adjustment means at one end anda toroidally shaped reversing deflector at the opposite end and whereinthe interface between said support member and said toroid is concave.

7. The apparatus of claim 1 wherein said liquid nozzle orifice means isan annulus.

8. The apparatus of claim 1 wherein said liquid nozzle: orifice meanscomprises a plurality of circumferentially' placed apertures incommunication with the liquid cavity/ and proximate to said resonator.

9. The apparatus of claim 1 wherein said liquid nozzle: orifice meanscomprises a plurality of jet nozzles disposed in the end portion of saidliquid nozzle proximate said resonator.

10. The apparatus of claim 1 wherein said liquid nozzle orifice meanscom-prises a plurality of radial bores in communication with said liquidcavity proximate to said resonator.

11. The apparatus of claim 1 wherein said cavity resonator comprises aninner side wall, a radially spaced outer side wall parallel to and ofshorter length than said inner side wall and an end wall connecting saidinner and outer side walls, the lower end of said longer, inner sidewall being positioned proximate to the annular groove of said reversingmeans to define a choked gas nozzle therebetween.

12. The apparatus of claim 11 wherein said open end of said resonator iscloser to the longitudinal center line of said generator than is saidend wall of said resonator.

13. The apparatus of claim 11 wherein said resonator side walls areparallel to the longitudinal center line of said resonator.

14. The apparatus of claim 11 wherein said open end of said resonator isfarther away from the longitudinal center line of said generator than issaid end wall of said resonator.

15. The apparatus of claim 1 including metal melting means incommunication with the liquid inlet means.

References Cited by the Examiner UNITED STATES PATENTS 2,519,619 8/1950Yellott et al. 2394 3,064,619 11/1962 Fortman 116-137 3,070,313 12/1962Fortman 2394 3,081,946 3/1963 Soloff 2394- EVERETI W. KIRBY, PrimaryExaminer.

1. A LIQUID SPRAYING APPARATUS EMPLOYING AN ACOUSTIC GENERATORCOMPRISING: (A) A BODY MEMBER INCLUDING INDEPENDENT GAS AND LIQUIDCAVITIES IN COMMUNICATION WITH GAS AND LIQUID INLET PORTS, RESPECTIVELY,THE GAS AND LIQUID CAVITIES BEING CONCENTRICALLY DISPOSED WITH RESPECTTO EACH OTHER; (B) A GAS DISPENSING OUTLET EXTENDING FROM SAID BODYMEMBER IN A DOWNSTREAM DIRECTION, SAID GAS DISPENSING OUTLET HAVING ABORE CONTIGUOUS WITH THE GAS CAVITY; (C) A GAS FLOW REVERSER MEMBERRIGIDLY SUPPORTED FROM SAID BODY MEMBER IN SPACED RELATION TO SAID GASDISPENSING OUTLET, SAID REVERSER MEMBER BEING PROVIDED WITH A CONCAVEUPWARDLY FACING ANNULAR GROOVE IN OPPOSITION TO SAID GAS DISPENSINGOUTLET, THE ANNULAR GROOVE BEING NONRESONANT TO THE FLOW OF GASTHERETHROUGH; (D) AN ANNULAR CAVITY RESONATOR DEPLOYED IN SAID BODYMEMBER COAXIAL WITH SAID GAS DISPENSING OUTLET; AND (E) LIQUID NOZZLEORIFICE MEANS CARRIED BY SAID BODY MEMBER, SAID LIQUID NOZZLE ORIFICEMEANS BEING DEPLOYED IN CONCENTRIC RELATIONSHIP TO SAID CAVITY RESONATORAND IN COMMUNICATION WITH THE LIQUID CAVITY.